The use of fluorescent lamps to illuminate a room or other area is well known in the lighting field. Many conventional luminaires for fluorescent lamps are designed to hold one or more standard-sized tubular fluorescent lamps. For example, some conventional luminaires are designed to hold one or more “T8” fluorescent lamps, wherein the T8 designation indicates that the lamp is tubular and has a diameter of one inch. While the tubular lamps are produced in a wide variety of lengths, a typical conventional luminaire design will only support lamps of a single predetermined length.
In some applications, conventional luminaires for fluorescent lamps are attached in an end-to-end fashion. Attaching luminaires in this manner effectively creates a single luminaire that is made up of several smaller lamps. This is advantageous over a single very long lamp in that shorter tubular lamps are generally less expensive and easier to store than longer lamps. Moreover, in some cases, the total length of attached luminaires can be as long as two hundred feet. When luminaires approach this length, connecting multiple smaller luminaires is the only reasonable solution.
Recently, various users of lighting have become more conscious of their energy use—either as a result of environmental concerns, budgetary concerns, or government regulation—and have sought out methods of reducing their energy use while still providing sufficient lighting to meet their needs. A conventional solution to this problem is the use of motion sensors to control luminaires. Conventional motion sensors are configured to turn the luminaires they control off when the motion sensor has not detected any motion for a predetermined period of time, and to turn the luminaires on when the motion sensor detects motion.
However, the installation of motion sensors can be a costly and cumbersome task. Conventional motion sensors are typically installed either in the ceiling, or on the luminaire itself. Installing a motion sensor in the ceiling requires additional wiring that may not be present in older buildings, and also may result in inefficient placement of motion sensors.
Installing a motion sensor directly on a luminaire can alleviate the need to provide additional wiring, as the motion sensor can control at least the luminaire on which it is installed. Installing a motion sensor directly on a luminaire, however, results in additional problems. First, conventional motion sensors tend to be large—often at least four inches in diameter. A location for the installation of the motion sensor on the luminaire must be provided, which generally results in increasing the length of the luminaire to accommodate the motion sensor. Accordingly, a purchase of new luminaires may be required to retrofit existing facilities with motion sensors.
Second, because an installed motion sensor adds length to a conventional luminaire, the advantageous feature of installing luminaires in series, as described above, becomes less attractive, as the additional length needed to accommodate a motion sensor is multiplied over a long run, adding, for example, four inches for every eight feet of lamps. For example, in very large facilities, such as large warehouses and factories, luminaires may need to be upward of two hundred feet long. Adding four inches for every eight feet of lamps adds over eight feet (or nearly five percent) to the length of the luminaire solely to accommodate the motion sensors. Not only does this additional length result in an undesirable use of space, the additional length makes the alignment of the luminaire with other luminaires that may or may not have motion sensors installed difficult, if not impossible. Furthermore, the additional length added by the motion sensor results in a portion of the luminaire that does not include a lamp, and therefore is not providing light to the surface below. This may result in reduced light levels in certain areas that may not be safe, and may not comply with local building codes or other regulations. Moreover, in facilities having fixed supports for mounting conventional luminaires in the ceiling, the additional length can make the installation of luminaires having motion sensors infeasible because of the cost of adjusting the ceiling supports.
Accordingly, a need exists in the art for a motion sensor that can be installed in a luminaire designed to accommodate tubular fluorescent lamps such that the motion sensor can be installed without adding additional length to the luminaire. A need also exists in the art for a system of adding multiple motion sensors to long rows of fixtures that does not result in the misalignment of fixtures across different rows.